Spring unit for cushion spring assemblies



May 3, 1960 J. G. PLATT SPRING UNIT FDR CUSHION SPRING ASSEMBLIES FiledJune 27, 1958 John 6: Fla/f Aria/wax 2,935,124 Fate-mated May"3,- 1960lie SPRING UNIT FQR CUSHION SPG V ASSEMBLIES John G. Piatt, Carthage,Mo., assignor to Fiex fi-Lators, Inc., Carthage, Mo., a corporation ofMissouri Application June 27, 1958, Serial No. 744,955

Claims. (Cl. 155-179) This invention relates to new and usefulimprovements in cushion spring assemblies for furniture, automotiveseating and the like, and has particular reference to spring assembliesof the type comprising a series of substantially planar spring unitsdisposed in spaced apart vertical planes and each connected to afurniture frame only at its opposite ends.

An important advantage of the above type of spring units has been thatsince they aresubstantially planar, they may be packed flat in a verycompact package for handling, storage and shipping, thus overcoming theusual disadvantage of'other spring units which are extremely bulky inproportion to their weight and hence difiicult to store and expensive toship. They are also quite economical. in cost, simple to install, and donot require specially fabricated or complicated furniture frames toaccommodate their use.

On the other hand, spring units of the type described have been subjectto certain disadvantages, particularly with regard to obtaining anassembly having the desired characteristics of yieldability over theentire area of a spring deck produced from such units. Specifically,spring assemblies produced from these units have exhibited a pronouncedtendency to sag excessively in the portion thereof midway between thesecured ends of the units, since the units are secured only at theiropposite ends and must of necessity have a considerable span. Attemptsto stiffen the mid-portion of the load-supporting deck to preventsagging as described, have generally resulted in a structure which isobjectionably stiff or hard when a person first applies his weightthereto. An important object of the present invention is, therefore, theprovision of a spring unit of the character described having novel meansfor stiffening the mid-portion thereof to prevent excessive sagging asabove discussed, and which nevertheless will initially be sufficientlyyieldable to preserve the feeling of depth and luxury so essential inmodern seating. The central stiffening means, for this reason, arecomparatively inactive during the initial compression of the units, butbecome increasingly effective as a greater load is applied and thedeflection becomes correspondingly greater.

1 Another disadvantage of spring units of this type has been that sincethe load-supporting deck of the assembly must of necessity be disposedwell above the level of the furniture frame to which the ends of theunits are secured, there must be vertically extending spring portionsbetween the spring ends and the portions thereof forming the deck. Thesevertically extending portions are of course resiliently yieldable, andhence can move horizontally, with the result that the deck can sway fromside to side in any direction. This lack of horizontal stability, eventhough slight, can be disconcerting to the -user, and definitelydetracts from the comfort of the cushion. Another object of the presentinvention is, therefore, the provision of means for horizontallystabilizing ;the;unit s to minimize such swaying.

ability for use in many types and varities of furniture. I

With these objects in view, as well as other objects which will appearin the course of the specification, reference will be had to thedrawing, wherein:

Fig. 1 is a top plan view of a cushion spring assembly comprising springunits embodying the present invention,

Fig. 2 is a sectional view taken on line 11-11 of Fig. l, with partsbroken away, and

Fig. 3 is an enlarged sectional view taken on line III-III of Fig. 2.

Like reference numerals apply to similar parts throughout the severalviews, and the numeral 2 applies generally to a furniture frame which byway of example will hereinafter be referred to as a seat frame, althoughit will be readily apparent that the concepts involved are equallyadaptable to back frames, couches, automotive seating, .and in nearlyany application involving spring cushions. Said frame as shown isformedvof wood and is of rectangular form, comprising a front rail 4,back rail 6, and parallel, spaced apart side rails 8, all rigidly joinedtogether in a unitary structure. A plurality of spring units eachembodying the present invention and each designated generally by thenumeral 10, are mounted insaid frame. Each of said units isapproximately planar, and said units are disposed in vertical planesspaced regularly across the width of frame 2. Each of said spring unitscomprises a main spring 12, a secondary or auxiliary spring 14, and astabilizing spring 16, all formed of fiat spring steel stock or othersuitable material.

Main spring 12 includes a substantially straight central portion 17which is disposed above and approximately parallel to the plane of theframe, and which in conjunction with the like portions of the otherunits forms the load-supporting platform ordeck of the assembly. At theforward end of section 17, the main spring is bent to form,successively, a forwardly and up wardly inclined bight or loop 18, arearwardly and downwardly inclined leg 20, bend 22, a forwardlyextending leg 24, and a downwardly extending terminal leg 26 adapted tobe secured to front rail 4 of the frame. At the rearward end of centralsection 17, the main spring is bent to form successively, a bend 28, aforwardly and downwardly inclined leg 30, bend 32, a downwardly andrearwardly inclined leg 34, and a downwardly extending terminal leg 36adapted to be secured to back rail 6 of the frame.

Secondary spring 14 is shaped somewhat similarly to the main spring,having a horizontal central portion 38 disposed beneath and inengagement with central port-ion 17 of the main spring but of shorterspan than portion 17, and being secured thereto intermediate its ends bya rivet 40. At the forward end of portion 38, the secondary spring isbent to form, successively, a bend 42, a downwardly and rearwardlyinclined leg 44 contacting leg 20 of'the main spring, a bend 46 engagingbend 22 of the main spring, a forwardly extending leg 48 lying beneathleg 24 of the main spring and affixed thereto by rivet 50, and .adownwardly extending terminal leg 52 adapted to be secured to frame rail4. Spring legs 26 and 52' are both secured to rail 4 by a common setoffasteners such as nails 54. At the rearward end of portion 38, thesecondary spring i bent to form, successively, a bend 56, a downwardlyand forwardly inclined leg 58, bend 60, a downwardly and rearwardlyinclined leg 62 which lies against leg 34 of the main spring and issecured thereto by rivet 64, and a downwardly extending terminal leg 66adapted to be secured to frame rail 6. i t

Stabilizing spring 16 has one end portion 68 thereof Other objects aresimilicity and economy of construcsecured to the central portions 17 and38 of the main and secondary springs by rivet 40, and extends forwardlyfrom its point of attachment. It is then bent to form, successively, abend 70, a downwardly and rearwardly inclined leg 72 which lies beneathand in contact with leg 62 of the secondary spring and is securedthereto by rivet 64, and a downwardly extending terminal leg 74 adaptedto be secured to frame rail 6. The rearward terminal legs of all of thespring members are secured to rail 6 by a common set of fasteners suchas nails 76.

All of spring units 10 are interconnected and stabilized againstmovement transverse to their planes by a plurality of flexible steel tiestrips 78 extending transversely across the load-supporting deck of theassembly, each of said strips being secured to the central portion 17 ofeach main spring at its point of intersection therewith, as by a rivet.The illustration shows two such tie strips disposed respectivelyadjacent the forward and rearward edges of the deck, and secured byrivets 80, and a third tie strip disposed intermediate the front andrear edges of the deck and secured by rivets 40, although a larger orsmaller number of strips could obviously be used if desired. It will beunderstood that the spring assembly as shown is in actual use covered bysuitable layers of padding and upholstery.

The operation of the spring assembly is substantially as follows: Atleast two features contribute to a stiffening or reinforcing of thecentral portion of each spring unit 10 whereby to prevent excessivesagging thereof when loaded. Firstly, the fact that the rearwardlyextending legs 34, 62 and 72 of the main, secondary and stabilizingspring members are rigidly secured together by rivet 64, and forwardlyextending legs 24 and 48 of the main and secondary springs are securedtogether by rivet 549, provides that each unit has end portions whichare effectively much stiffer than the central portion, since the endsections are of double or triple thickness and must flex as a unit. Thusthe unit is rendered of more uniform strength from end to end in muchthe same manner as would be provided by a multi-leaf spring wherein theleaves are of graduated lengths, and the effective points of support forthe central deck portions are moved'inwardly from rails 4' and 6.Secondly, secondary spring 14 and auxiliary spring 16 provide additionaldirect support under the central portion 17 of the main spring to bracethe same against undue deflection. In this connection, two specialprovisions should be noted. First, it will be seen that forward bend 42of the secondary spring, which is relatively rigid as compared to anextended length of the spring, is seated directly be tween centralportion 17 and leg 20 of the main spring, while the portions of thesecondary and stabilizing spring at the rearward end section of mainspring section 17 not only do not seat on leg 3% of the main spring, butare spaced respectively at substantial distances forwardly from leg 30.This relationship provides that the forward edge of the cushion will beslightly stiffer, that is, will have a slightly greater resistance toinitial downward deflection, than the rearward edge. This. defeats anytendency of the deck to tilt forwardly as a person applies his weightthereto, and on the contrary produces a very slight rearward tilting.This is conducive to comfort as it, tends to move the person toward theseat back (not shown) and hold him firmly in the seat. On the otherhand, any tendency toward forward tilting creates a sensation ofslipping out of the seat, and is distinctly uncomfortable. Secondly, thecompound leg formed by leg 34 of the main spring and the portions oflegs 62 and 72 of the secondary and stabilizing springs, which aresecured to leg 34 by rivet 64, yields a relatively small distance ascompared to central portion 17 of the main spring as a load is appliedthereto, and there is therefore a substantial relative movement betweensection 17 and leg 34. Also, the portions of legs 62 and 72 extendingforwardly from rivet 64 are initially unstressed, and it will beapparent that they will not supply appreciable support to section 17until section 17 has been deflected sufliciently, relative to leg 34, toflex the forward portions of legs 62 and 72, relative to leg 34. Thusthe section 17 is initially relatively soft and yieldable, but becomesprogressively, firmer as .the secondary and stabilizing springs arebrought into play as described. Excessive yieldability or sagging'of theassembly is therefore prevented, while at the same time preserving theinitial softness or yieldability which is necessary to a feeling ofluxurious comfort or depth.

Stabilizing spring 16 also has the valuable function of preventing undueforward and rearward movement or swaying of the deck portions 17 of theunits. Were it not for the stabilizing spring, the double bend at eachend of section 17, and at' each end of the secondary spring would permitsuch movement, That is, for example, a forward movement of a personsitting on the cushion would cause an opening or straightening action onbends 28 and 32 of the main spring and bends 56 and 60 of the secondaryspring, and a closing action on bends 18, 22, 42 and 46 of the main andsecondary springs, and section 17 would move forwardly. Such a movementcreates a feeling of instability and discomfort,

. and is also accompanied by a tilting or rocking movement which causesfurther discomfort. The stabilizing spring 16, however, has only asingle bend 70 therein between main spring section 17 and its point ofattachment to rail 6. Therefore a mere opening action of bend 7 0, asdistinguished from the double bends of the main and secondary springs,will not permit any appreciable forward movement of the upper end of thestabilizing spring. Forward movement at this point would require thatbend 70 to be unrolled by opposite longitudinal forces in the spring atopposite sides of the bend, and the spring is relatively highlyresistant to this type of deformation.

Bend 70 could of course be eliminated, and spring 16 extendedsubstantially straight to a point of attachment to main spring section17. This would provide the forward and rearward stabilization asdiscussed, but would be too' severe in that it would prevent any degreewhatsoever of forward movement. Such absolute stabilization is in itselfundesirable, as complete immovability of the deck in any directioncreates an anchored or tethere'd" feel which is not conducive tocomfort. The single bend 70 has been found to produce adequate stabilityand still to be sufficiently yieldable for comfort. Spring 16 alsostabilizes against rearward movement, since rearward movement places leg72 thereof in compression, and since said leg is supported along most ofits length by its proximity and attachment to legs 34 and 62 of the mainand secondary springs.

While I have shown and described a specific embodiment of my invention,it will be apparent that many minor changes of structure and operationcould be made without departing from the spirit of the invention asdefined by the scope of the appended claims.

WhatI claim as new and desire to protect by Letters Patent is:

l. A spring unit for use in a cushion spring assembly comprising aplurality of such spring units disposed in substantially parallel,horizontally spaced apart vertical planes ina suitable frame, saidspring unit comprising a main spring formed of a single length'ofresilient ma- 'terial having a generally straight central portiondisposed generally horizontally above said frame and an inwardlyconverging V-formation at each end of said central portion, saidV-forrnations having upper and lower legs and being adapted to besecured at their lower ends to said frame, and a secondary spring formedsimilarly to said main spring, the central portion thereof being ofshorter span than but disposed directly beneathand aifixed to thecentral portion of said main spring, and the V-formations at the endsthereof also being adapted to be afiixed to said frame, the upper leg ofthe V-formation, at one end of said secondary spring being seateddirectly on the corresponding leg of said main spring, and the lower legof the V-formation at the opposite end of said secondary spring issubstantially longer than the corresponding leg of said main spring,whereby the upper legs of the V- formations at this end are spacedsubstantially apart.

2. A spring unit as recited in claim 1 wherein the lower legs of the.V-formations at both ends of theunit are rigidly secured together toform legs of greater thickness and stiifness.

3. A spring unit for use in a cushion spring assembly comprising aplurality of such spring units disposed in substantially parallel,horizontally spaced apart vertical planes in a suitable frame, saidspring unit comprising a main spring formed of a single length ofresilient material having a generally straight central portion disposedgenerally horizontally above said frame and an inwardly convergingV-formation at each end of said central portion, said V-formationshaving upper and lower legs and being adapted to be secured at theirlower ends to said frame, and a secondary spring formed similarly tosaid main spring, the central portion thereof being of shorter span thanbut disposed directly beneath and aflixed to the central portion of saidmain spring, and the V-formations at the ends thereof also being adaptedto be aflixed to said frame, and a stabilizing spring comprising alength of resilient material having upper and lower legs connected by asingle reverse bend, said upper leg being secured to the central portionof said main spring intermediate the ends thereof, and said lower legbeing adapted to be secured at its lower end to said frame.

4. A spring unit as recited in claim 2 with the addition of astabilizing spring comprising a length of resilient material having itsupper end portion secured to the central portion of said main spring andhaving a lower leg extending toward the end of said unit at which thelower legs of the V-formation is of the main and secondary springs areof unequal lengths, and adapted to be attached at its lower end to saidframe, the lower leg of said stabilizing spring being of greater lengththan the corresponding lower leg of the V-formation of the secondaryspring, and attached rigidly to the lower legs of the correspondingV-formations of the main and secondary springs.

5. A spring unit as recited in claim 4 wherein said stabilizing springcomprises upper and lower legs connected by a single reverse bend, theupper leg thereof being aifixed to the central pontion of said mainspring.

245,447 Chittenden Aug. 9, 1881 Mengel Aug. 1, 18s;

